1. Field of the Invention
The present invention relates to an ink-jet recording apparatus or head, or a cavity unit for use in the apparatus or head.
2. Discussion of Related Art
There has been known an ink-jet recording apparatus or head employing a cavity unit including a plurality of plate members that are stacked on each other and that has at least one ink-introducing passage which introduces an ink, a plurality of nozzles each of which ejects a droplet of the ink, a plurality of pressure chambers (i.e., individual ink chambers) each of which outputs the ink to a corresponding one of the nozzles, and at least one ink manifold (i.e., common ink chamber) which temporarily stores the ink to be supplied to each of the pressure chambers. When a pressure is applied to an arbitrary one or ones of the pressure chambers, a corresponding one or ones of the nozzles ejects or eject a droplet or droplets of the ink toward a recording medium, so as to record an image thereon.
Generally, the ink-jet recording head further has, at an open end of an upstream-side end portion of the ink-introducing passage, a filter that removes foreign matters from the introduced ink. In addition, Patent Document 1 (Japanese Patent Application Publication 2004-306540 or its corresponding U.S. Patent Application Publication 2004-257415) discloses a cavity unit including (a) a filter and (b) a plate member that has a thickness greater than that of the filter, surrounds the filter, and defines a flat space between the filter and an ink-supply member located on an upstream side of the filter. Since ink flows at high speeds in the flat space, air bubbles can be easily removed from the filter, i.e., easily prevented from standing on the filter.
Moreover, Patent Document 2 (Japanese Patent Application Publication 2003-311951 or its corresponding U.S. Pat. Nos. 6,692,109, 6,719,404, and 6,830,325) discloses an ink-jet recording head in which a plate member provided on an upper side of an ink manifold (i.e., a common ink chamber) has, at a position corresponding to an ink-introducing passage, a multiplicity of small through-holes that are formed through a thickness of the plate member and cooperate with each other to function as a filter.
Each of the above-indicated two filters is originally designed such that even if the each filter may be clogged to some degree with an expected amount of foreign matters gradually accumulated thereon, the each filter can function normally for a certain time period.